PERMIAN 87 



Protodonata, Megasecoptera and Blattidac. With the exception 

 of the last mentioned, all these groups are extinct to-day — they 

 are ancestral forms from which more recent types have been 

 derived. None of these early orders gives any clue as to the origin 

 of insects as a class, while their abundance, together with their 

 relatively high grade of specialisation in some cases, clearly 

 indicate that more ancient relics of insect life still await disclosure 

 in antecedent rocks. 



The primordial and heterogenous order Palasodictyoptera 

 appears to have already attained its maximum development 

 in the middle strata of the Upper Carboniferous and the famous 

 beds of Commentry in France, those of Mazon Creek in North 

 America and other beds of the same age in England and Belgium 

 have yielded many remarkable forms. This order, together with 

 the Megasecoptera, appears to have declined relatively quickly, 

 and towards the end of the Carboniferous age their remains 

 become very scanty. In addition to the orders mentioned, a 

 number of isolated fossils of doubtful affinities occur during this 

 age, and have been raised by Handlirsch to the rank of separate 

 orders. Among them are the j3rimordial mayfly, Triphlosoba 

 Handl.j which forms the sole representative of Handlirsch's order 

 Protephemeroidea, and the Hadentomoidea, which he regards as 

 forerunners of the Embioptera. 



Many of the Carboniferous insects were of large size, and 

 included some of the giants of their class. For the most part they 

 appear to have been slow and weak fliers, a feature which may 

 have contributed to their early extinction. The Blattidse, however, 

 are an exception, since they have retained their general facies, 

 with comparatively slight modifications, down to the present day. 



Permian. Recent discoveries, previously alluded to, have 

 revealed a rich and highly interesting fauna in Permian times. 

 In rocks of Lower Permian date are found the earliest known 

 Holometabola which are represented by several families of 

 Mecoptera (i;i<i^ Tillyard, 1935 ; Carpenter, 1930a) and Neuroptera 

 (Tillyard, 1932). Of the Mecoptera the family Permochoristida; 

 has thirteen species in five genera, while the single species of 

 Anomochorista gives its name to a second family. It is remarkable 



